I use Roon and have the same scenario. Roon sees the microrendu (same with Ultrarendu),but not the DAC connected to it via usb. Been that way for years.
No connectivity to Micro Rendu device
I have new iMac with a cable moden connecting via ethernet cable to the MR to my Aqua LaVoce DAC. I use Audirvana and it sees the MR but does not see the DAC. I have spent hours and hours DXing the problem and have failed. Neither Sonicorbiter nor Audirvana have been of any assistance. The MR is a vital addition to my system -- when it functions, which is very rare. Can anybody help me out? Thanks.